1. Field of the Invention
This invention relates to automatic power transmissions providing a plurality of gear reduction ratios, such as automatic mechanical transmissions (i.e. "AMTs"), and, to control systems and methods therefor. In particular, the present invention relates to control systems and methods for automatic mechanical transmission systems wherein gear selection and shift decisions are made and/or executed based upon measured and/or calculated parameters such as vehicle or transmission output shaft speed, transmission input shaft speed, engine speed, throttle position, rate of change of throttle position, rate of change of vehicle and/or engine speed and the like. More particularly, the present invention relates to a method for controlling an AMT system during a vehicle start from stop operation including controlling both the master clutch and the fuel supply to the engine.
2. Description of the Prior Art
The use of automatic transmissions of both the automatic mechanical type utilizing positive clutches and of the planetary gear type utilizing frictional clutches is well known in the prior art as are control systems therefor. Electronic control systems utilizing discrete logic circuits and/or software controlled microprocessors for automatic transmissions wherein gear selection and shift decisions are made based upon certain measured and/or calculated parameters such as vehicle speed (or transmission output shaft speed), transmission input shaft speed, engine speed, rate of change of vehicle speed, rate of change of engine speed, throttle position, rate of change of throttle position, full depression of the throttle (i.e. "kickdown"), actuation of the braking mechanism, currently engaged gear ratio, and the like are known in the prior art. Examples of such automatic /semiautomatic transmission control systems for vehicles may be seen by reference to U.S. Pat. Nos. 4,361,060; 4,551,802; 4,527,447; 4,425,620; 4,463,427; 4,081,065; 4,073,203; 4,253,348; 4,038,889; 4,226,295; 3,776,048, 4,208,929; 4,039,061; 3,974,720; 3,478,851 and 3,942,393, the disclosures of which are all hereby incorporated by reference.
Automatic control systems/subsystems for automatically controlling the engagement and disengagement of AMT system vehicle master clutches, especially during vehicle start from stop operations, are known in the prior art as may be seen by reference to U.S. Pat. Nos. 4,081,065; 4,401,200; 4,413,714; 4,432,445, 4,509,625 and 4,576,263, the disclosures of all of which are hereby incorporated by reference.
While the above referenced automatic/semiautomatic transmission control systems, especially the system illustrated in U.S. Pat. Nos. 4,081,065 and 4,576,263 and similar systems, are effective to control the vehicle master clutch during start from stop operations under most conditions, under certain conditions, if fuel is allowed to supplied in accordance with throttle pedal setting, the clutch may not engage in a manner sufficiently rapid to control the engine (i.e. prevent the engine from undesirably racing at a higher than desired rotational speed) and/or may not provide an acceptably smooth engagement of the clutch.